US20140183300A1 - Tethered payload system and method - Google Patents

Abstract

A vehicle, especially a maritime vessel, is provided with an autogyro drawn by a tether. The tether contains mechanical strengthening components that enable it to securely retain the autogyro to the vehicle. The tether also contains two electrical conductors carrying different phases of AC power to the autogyro, and four optical fibers carrying optical data signals to and from the autogyro electronic payloads and avionics control circuitry. Signal converters at ends of the tether convert a wide range of electrical or wireless signals to optical data signals for transmission along the tether, and then back into the original electrical signal format for use by the autogyro or vehicle electronics.

Description

RELATED APPLICATIONS
• This application claims the benefit of U.S. provisional application Ser. No. 61/641,279 filed on May 1, 2012, and of U.S. provisional application Ser. No. 61/509,718 filed on Jul. 20, 2011.
FIELD OF THE INVENTION
• This invention relates to systems and methods of electronic communications or surveillance, and more particularly, such systems with or methods employing an elevated antenna and electronic subsystems supported on an airborne platform drawn behind a moving land vehicle or sea-going vessel.
BACKGROUND OF THE INVENTION
• A number of governmental defense or law enforcement agencies require real-time intelligence in order to successfully execute their respective missions to protect national security and related interests.
• There is a multitude of electronic intelligence, surveillance and reconnaissance (collectively “ISR”) capabilities available to military and law enforcement that are limited in practice because the radio or other electromagnetic signals generally require a line-of-sight for operation, and geographic constraints, including the terrain with e.g., intervening mountains, within which they must perform, limit the range of their operation.
• In addition to ISR capabilities, other military and law enforcement technologies are restricted by “height of eye” considerations that define the distance to the horizon, and limit the distance of the operation due to the curvature of the earth. These technologies include radio frequency jamming, electronic attack, computer network operations and exploitation, laser targeting, and weapon countermeasure systems.
• These tasks are further complicated by the need for clandestine operations in an environment of challenging terrain, range, limited manpower, and other operational and environmental concerns, that make solving the problem by a direct approach, such as by building a sensor or broadcast tower high enough to operate above the obstructing terrain or to extend the height of eye and the horizon, prohibitive in cost or impossible.
• Historically, tethered balloons were used to extend the line of sight in military situations. In the surveillance context, balloons are undesirable, because they require a large footprint on the deck of a vessel, or a large ground area and a substantial number of personnel are required to act as ground crew. Furthermore, balloons are very large, and therefore visible, making surveillance less stealthy.
• Another issue that also may arise with respect to prior art systems is that use of wires to communicate electronically with the aerial vehicle may present a concern for stealth or electronic warfare operation, in that it may be possible to intercept, interfere with or spoof the communication between the land vehicle and the aerial vehicle.
• These and other constraints imposed by systems operating with a limited “height of eye” or line of sight can render the execution of military, homeland security and law enforcement missions more difficult.
SUMMARY OF THE INVENTION
• It is accordingly an object of the invention to provide a system and a method of electromagnetic-based and electro-optic interaction that overcomes the issues of height of eye or other obstruction such as curvature of the earth or terrain.
• It is further an object of the invention that a tethered payload system of the invention overcomes the deficiencies of prior art and provides an enduring and clandestine method of real-time data intelligence/surveillance in threat environments that have limited visual range.
• It is further an object of the invention to provide an airborne platform with one or more sensors, countermeasures, communications, and/or targeting capabilities, which airborne platform is deployed at selectable altitudes utilizing an airborne vehicle capable of carrying aloft payloads, e.g., sensors, most preferably electromagnetic signal sensors such as radio frequency (RF), electro-optic (EO), infrared (IR), or radio communications, or transmission devices, including, e.g., countermeasures and LASER targeting, or systems that employ both transmission and reception of electromagnetic waves, e.g., radar of the various types used in civilian and military applications.
• It is further an object of the invention to provide a tethered payload system with a platform that overcomes the line-of-sight restrictions and endurance restrictions resulting from current surveillance system power requirements while requiring minimal manpower to operate.
• According to an aspect of the invention, the tethered payload system operates as the interface platform for operation of the payload situated upon an airborne vehicle, for example, an autogyro, tethered to an in-motion host vehicle, either a maritime or ground vehicle. The tethered payload systems include the airborne vehicle, a payload sensor suite, a launch and recovery system, a data aggregation subsystem (DAS), Payload Sensor Human Machine Interface (HMI), and payload power system. The tethered payload system design is scalable to address smaller or larger payloads, as well as smaller or larger host vehicles accordingly.
• According to another aspect of the invention, the tethered payload system includes a novel data aggregation subsystem (DAS) that is capable of multiplexing/demultiplexing analog radio frequency (RF), analog and digital video, Ethernet, and discrete voltage signals, e.g., Transistor-Transistor Logic (TTL), over a full-duplex fiber-optic link. A software application packages and distributes sensor data to the host vehicle's command and control center, or a human machine interface (HMI).
• The HMI may be made from a combination of COTS and custom software. The HMI host computer performs mass storage of sensor data provided from the vehicle payloads, and may also be configured to send the sensor data to a control center of the host vehicle or to another host-vehicle sensor management system. Dependent on payload, the HMI may also perform basic sensor-data filtering and electronic ID functions.
• According to an aspect of the invention, a tethered payload system receives power, signal, and other electrical-type support, e.g., lightning protection, through a tow cable to a power conditioning and signal distribution center on the airborne airframe platform. The power conditioning and signal distribution center provides power to the payloads, and dependent upon the needs of the users on the host vehicle or the payloads themselves, the distribution center can selectively provide relatively more or less power. As an option, batteries can be used onboard the tethered payload system to augment or replace cable provided power in smaller configurations. The tow cable also can provide lightning protection by including a braided shield electrical conductor line electrically grounding the airframe to earth ground through the host vehicle.
• According to still another aspect of the invention, a method for interaction with an environment around a vehicle comprises providing an airborne platform connected by a tether to the vehicle. The airborne platform remains aloft at least in part by airflow relative to the airborne platform. Electrical power is transmitted from the host vehicle to the airborne platform via power conductors in the tether. The electrical power is received in airborne electronic payload circuitry on the airborne platform, and the airborne electronic payload circuitry uses the electrical power to engage in the interaction with the environment. Upward optical data signals are carried between the vehicle and the airborne platform via an optical fiber in the tether. The upward optical data signals received at the aerial platform are converted to received electrical signals and the received electrical signals are provided to the payload circuitry. Local electrical signals are generated in the payload circuitry responsive to the interaction with the environment. The local electrical signals on the aerial platform are converted to downward optical signals. The downward optical data signals are transmitted to the vehicle via the optical fiber, or via another optical fiber in the tether.
• According to another aspect of the invention, a system provides a vehicle with electronic operations at a distance from the vehicle. The system comprises a tether connected with the vehicle and extending upwardly therefrom. An airborne platform is connected with the tether and secured thereby so as to remain aloft in an area of the vehicle at least partly by airflow relative to the aerial platform. The airborne platform has airborne electronic payload circuitry supporting the electronic operations, and the tether includes an electrical conductor supplying electrical power from the vehicle to the aerial platform. The tether includes at least one optical fiber linked with the airborne electronic payload circuity and with electronic base circuitry on the vehicle. The optical fiber in the tether carries optical data signals to the airborne platform from the vehicle or to the vehicle from the airborne platform such that the electronic base circuitry on the vehicle co-acts with the airborne electronic payload circuitry during the electronic operations.
• According to another aspect of the invention, an airborne platform provides electronic surveillance, communication or electronic warfare or defense capabilities. The airborne platform comprises an autogyro configured to be secured to an end of a tether having conductors carrying AC current and optical fibers carrying optical signals. The autogyro includes a frame supporting a rotor with rotor blades providing lift from passing air, and a stabilizer structure with control surfaces. The frame supports a generally cylindrical module supporting therein payload electronics configured to support the electronic surveillance, communication or electronic warfare or defense capabilities and avionic electronics controlling flight operation of the autogyro. The module receives the AC current and the optical signals from the tether. The module has a power converter converting the AC current to DC current and supplying the DC current to the payload and avionic electronics, and a signal converter converting the optical signals into electrical signals and transmitting the signals to the payload and avionic electronics.
• According to still another embodiment of the invention, a system links a round vehicle with an airborne platform. The system comprises a tether having a mechanical portion providing sufficient tensional strength for retaining the airborne platform connected by the tether to the ground vehicle. A metallic electrical conductor extends from a first end of the tether to an opposing second end of the tether, and it is configured to transmit AC current having a voltage of at least 400 volts and a power level of at least 600 watts. At least one optical fiber extends from the first end to the second end of the tether. There are first and second converters at the first and second ends of the tether, respectively. Each of the converters comprises an electrical connection receiving incoming electrical signals, and an electrical-to-optical conversion unit connected with the electrical connection and converting the incoming electrical signals to outgoing optical signals and transmitting the outgoing optical signals over the optical fiber. The converter further comprises an optical-to-electrical conversion unit receiving incoming optical signals transmitted through the optical fiber and converting those incoming optical signals to outgoing electrical signals and transmitting the outgoing electrical signals to the electrical connection.
• Payload and control data is transmitted and received via fiber-optic cable embedded within the tow cable. This method of transmission provides a secure data link with a low-probability of detection or interception, as well as being resistant to counter-measure jamming.
• Other objects and advantages of the invention will become apparent from the specification herein.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a schematic diagram of a vehicle, here a sea-going vessel, employing a system according to the invention.
• FIG. 2 is a graph showing the relationship between the height of a sensor and the distance to the visible horizon at that height.
• FIG. 3 is an elevational-view diagram of an autogyro for use as an airborne platform according to the invention.
• FIG. 4 is a plan-view diagram of an autogyro for use as an airborne platform according to the invention
• FIG. 5 is a schematic diagram of a system according to the invention.
• FIG. 6 is a diagram of the tether of the system ofFIG. 5 and its connections.
• FIG. 7 is a cross-sectional view of the tether.
• FIG. 8 is a diagram of an exemplary set of payloads with supporting systems in the base vehicle.
• FIG. 9 is a diagram of the optical fiber communication signal conversion and de-conversion according to the invention.
• FIG. 10 is a diagram of an exemplary converter converting electrical signals to and from optical signals in the optical fibers of the tether.
• FIG. 11 is a diagram of the launch and recovery platform.
• FIG. 12 shows the steps of launch and recovery of the vehicle using an articulable arm and platform arrangement.
• FIG. 13 is a perspective view of an alternate embodiment of the autogyro.
• FIG. 14 is a side view of the aft cylinder of the autogyro according to the invention.
• FIG. 15 is a cross sectional view as inFIG. 14, showing the interior structures in the cylinder.
• FIG. 16 is a detail view of the solenoid and watertight closing structure on one end of the cylinders.
• FIG. 17 is a side elevational view of another alternate embodiment of the autogyro.
• FIG. 18 a top view of the autogyro ofFIG. 17.
• FIG. 19 is a front elevational view of the autogyro ofFIGS. 17 and 18.
• FIG. 20 is a diagram illustrating a converter in which more than one signal is transmitted over an optical fiber.
DETAILED DISCLOSURE
• Referring toFIG. 1, a host vehicle, in the diagram sea-goingvessel1, draws behind it atether line3. A small, unmannedairborne vehicle5, for example an autogyro, is towed by thetether line3. The water-bornevessel1 may be of any configuration, and may be as small as an 11-meter Rigid Hull Inflatable Boat (RHIB), or any larger water-borne or sea-going platform, provided that it can maintain a requisite minimum speed to keep the vehicle aloft. Thehost vehicle1 may also be a land vehicle that moves under power on land, drawing the airborne vehicle behind it.
• The autogyro typically has a simple unpowered rotor blade, and the host-vehicle forward motion produces a relative wind-speed with respect to the autogyro that generates lift without the need for additional power being generated, which provides operational endurance of theairborne vehicle5 aloft. At times there may be sufficient wind at the system's operating altitude that it can remain aloft with little to no forward motion of the host vehicle.
• The maximum altitude of operation of theairborne vehicle5 is dependent on a number of factors, including tether length, relative wind speed, payload weight, the desired sensor altitude, and the operating capabilities of the autogyro used. Generally, the operational altitude range of the system is from 50 feet to approximately 5,000 feet. However, for an airborne platform drawn by a ground vehicle, e.g., a Humvee, the practical operational altitude of the airborne vehicle is up to approximately 800 feet. Some maritime applications take advantage of an altitude up to 5,000 feet. However, an 800 foot elevation markedly improves the operation of surveillance in rough terrain, and operation at a range of up to approximately 2,000 feet or 4,000 feet also provides a substantial advantage.
• The graph ofFIG. 2 shows how the visible horizon can be extended for sensor detection as a function of the airborne vehicle's altitude. A usual line-of-sight visible horizon for a ship at sea with a sensor on the ship fairly high above the water is about 14 nautical miles. The horizon for radar is slightly more than that. An elevation of the sensor to even about 1500 feet more than triples that distance to horizon to almost 50 nautical miles. Range extensions of greater than three to one are therefore easily achieved by the system of the invention.
• The autogyro used for the platform may be any of a number of autogyros available on the market. The autogyro used in the invention is preferably one that is capable of remaining aloft indefinitely due to low power demands for maintaining itself stably at a predetermined altitude. To accomplish this, the autogyro has responsive flight control electromechanical mechanisms and other systems well known in the art that are controlled by flight control avionics electronic circuitry on the vehicle. That electronic circuitry acts responsive to flight control data signals sent to the airborne vehicle over communications lines in the tether, and allows for control of the flight of the vehicle form the base vehicle. Alternatively or at the same time, the flight control avionics electronics of the airborne vehicle may have a flight control system or autopilot system on board the vehicle that automatically performs control functions once initialized and does not require direct commands from the base vehicle.
• The autogyro provides lift starting at a predetermined minimum operating speed, and is operational for flight at any wind speed above that, up to a very high maximum relative wind speed. The minimum operating speed may be 5 knots or greater, but, especially where a large payload is involved, minimum operation speeds may be about 8 knots. The autogyro can operate at relative wind speeds well above the minimum speed, up to about 90 knots.
• In addition, the autogyro may have systems that can be briefly powered to provide propulsion during launch or landing if necessary, when the requisite relative wind speed is not immediately available. Similarly, these positive propulsion systems, e.g., auxiliary propellers, may be activated for a short period if the host vehicle temporarily stops its movement on the surface or changes its direction. Because the tethered payload system employing an autogyro is not weighed down with large engines and fuel, it has a reduction in size that equates to a reduction in radar cross-section, thereby providing additional stealth during operation without associated loss in surveillance capability.
• The autogyro is capable of supporting the weight of the payload, i.e., the sensor or other elevated electronics deployed in the aerial platform. This weight is at a minimum about 25 pounds, although for some applications a payload up to 75 pounds or even to 150 pounds may be required. In fact very large payloads, e.g., 2,000 pounds, may be accommodated by analogous systems scaled up to support the additional force loads.
• The autogyro of the preferred embodiment is much more stable than other systems that may be employed to create an airborne platform, such as a parasail or a kite. Stability is important, if not critical, to optimal operation of the elevated payload, and is an added benefit of use of the system of the invention with a vessel in rough seas, since the air above the ocean is typically not as turbulent as the water surface. The aforementioned other approaches, i.e., kites or parasails, are also generally larger, require more on-deck personnel for handling, and more visible, as well as requiring more vessel deck space for deployment, than an autogyro.
• An Embodiment of the Autogyro
• FIGS. 3 and 4 illustrate the general configuration of an autogyro for use according to the preferred embodiment. Theairborne vehicle5 comprises a main rotor blade assembly7 on amast9 extending upwardly from thebody11 of thevehicle5. Two blades are shown, but a three- or four-blade autogyro may also be employed.
• Thebody11 comprises two aligned generally cylindrical forward andrear modules13 and15 that house the operational electronics for thevehicle5.Nose member21 extends forward fromfront module13, and is pivotally connected with the end oftether3 by apivotal connection23.Cable20 links this pivoting point to a location on themast9 for support and transmission of loads in thevehicle5. Themodules13 and15 are supported betweenlongitudinal members17 that extend rearward to support atail structure19 that may have movable control surfaces for flight control, as is well known in the art. The rotor7 may also be adjusted in various ways known in the art to adjust the flight parameters ofvehicle5.
• Askid structure25 extends downward from thebody11 and supports thevehicle5 when on the ground or the deck of a vessel or other vehicle. Optionally,auxiliary propulsion systems27 are supported on the vehicle to provide temporary propulsion when relative wind speed drops temporarily below the minimum operational speed.
• Thetether3 is coupled to thevehicle5 atpivot connection23, and the force required to draw thevehicle5 along at operational wind speed is transmitted to the vehicle at this point. Thetether3 is made up of at least two components structurally, i.e., a mechanical cable that under tension draws thevehicle5 behind the host vehicle, a data connection, preferably fiber optics, and an electrical connection, preferably copper, that provides a data and power link between thevehicle5 and the host vehicle. At the aerial platform end of thetether3, these components are separated, with the mechanical cable linking toconnection23, and tiedata link lines31 extending to thefirst module13. Aprotective cone structure29 may be provided to cover and protectconnection21, as well as the separation of the power and data lines from the mechanical cable portion of thetether cable3.
• System Configuration
• FIG. 5 shows a diagram of the components of the system. The aerial platform orvehicle5 is connected via thetether3 to awinch system33 on thebase vehicle1.
• As best seen schematically inFIG. 6, thetether3 of the preferred embodiment comprises twoelectrical conductor wires30, and fouroptical fibers32 extending the full length of thetether3. One end of theelectrical conductors30 is connected with a step up transformer or powerconversion distribution unit37, which receives power from apower generator38 associated with thebase vehicle1. The distal end of the electrical conductors is connected with anelectrical power controller45 in theaerial vehicle5, which receives the power and distributes it to the various systems of theaerial vehicle5.
• Theoptical fibers32 are each connected at one end thereof with a broadband or radio frequency (or other electrical signal format)converter39 or49 that converts the electrical signal received to light and transmits it on one or more of theoptical fibers32. At the distal ends of theoptical fibers32, the signal is converted back to broadband, radio frequency (i.e., RF), or whatever other format was employed, byconverter39 or49. The resulting data or other electrical signals are supplied to theoperational circuitry51 of theaerial vehicle5, and transmitted to either the payload of thevehicle5 for electromagnetic interaction with the environment, or to flight control circuitry that operates theaerial vehicle5 with servo-systems, as are well known in the art.
• FIG. 7 shows a cross section of the tether cable itself. Acentral core71 is surrounded by four jacketed single modeoptical fibers32 of about 2.3 mm diameter, and two insulatedcopper wire conductors30 of 20 to 28 gauge.Filler material74 is between these wires and fiber. A strengtheningouter sheath73 of a particularly high-tensile-strength synthetic fiber material such as Kevlar™ or Vectran™ surrounds thesewires30 andfibers32, giving thetether3 its tensile strength for drawing the aircraft in flight. An extruded nylonouter cover75 surrounds theentire cable3.
• Thetether cable3 in the preferred embodiment has a diameter of about 0.38 inches in this embodiment and a breaking force of greater than 1000 pounds, and preferably at least about 4,000 and most preferably at least 5,000 pounds. The diameter of thecable3 is preferably less than 0.4 inches, but potentially may be of any diameter, so long as the cable has the requisite high strength, low weight per linear length, and can contain the fibers and conductors needed for operation. It may also be provided with another conducting wire inside themember73 or an external conductive sheath of the tether to carry electric charges from lightning down to be grounded at a grounded connection on the base vehicle. Its weight is preferably fairly low, e.g., about 60 pounds per 1000 feet or less. Suitable cable for practicing the invention may be readily obtained on the market, and may be obtained from; e.g., the Cortland Cable Co. in Cortland, N.Y.
• Referring toFIG. 5, thewinch system33 includes awinch35 that retains the tether or tow cable coiled and selectively reels it in or reels it out Preferably, the winch is hydraulic, remotely-operated winch, as is known in the art. It is preferably a 5 to 10 horsepower winch operating on 110 or 220 volt AC motor to drive the hydraulics. The winch is provided with a drum with fiber optic and electrical slip-rings or rotary joints, both of which are commercially available with numerous alternatives in the market. These joints provide for electrical and optical connection to the electrical and optical portions of thetether3 substantially without compromise due to twisting during reeling in and out of thewinch35. The spooling drum preferably has capacity for thousands of feet of cable, preferably 3,000 feet or more, and is self-leveling. Alternatively, a manual or smaller electric winch can be employed in certain applications.
• Thewinch35 allows for the electrical connection from power conversion/distribution module37, which receives power generated by thebase vehicle1 and provides AC current to theelectrical conductor portions30 oftether3 through the above described rotation-allowing electrical connections. The power conversion/distribution module37 converts the base vehicle power to 60 Hz AC current at a predetermined voltage that is appropriate to transmit up the tether to the airborne platform. The voltage is preferably in the range of 480 and 2000 volts, representing power of 700 to 2000 watts. The AC transmitted is two phases of AC, with each phase of the current being transmitted on arespective conductor30.
• Where thetether3 has a lightning suppression conductor, i.e., an additional braid of conductor linking theaerial vehicle5 to thebase vehicle1, the power conversion/distribution module37 provides lightning suppression by connecting that lightning conductor to ground. Other power surges, e.g., static charges, are also monitored and suppressed by the power conversion/distribution module37.
• A fiber-optic data encode/decode unit39 is connected with the fiber optic portion of thetether3 by the rotation-allowing optical connections, and supplies light signals thereto that are transmitted to thevehicle5, and receives optical light signals from the optical fibers of thetether3, and converts them to a form usable by the base vehicle systems.
• A launch andrecovery controller41 is connected with thewinch35 and the tether. The controller is a computerized control device that interfaces with and controls both thewinch35 and theaerial vehicle5, as well as a launch and recovery platform, if present, on the base vehicle, as will be described below.
• Theaerial platform5 at the opposite distal end of thetether3 hascircuitry43 that connects with theelectrical wires30 and theoptical fibers32 of thetether3. The circuitry includes power conversion anddistribution circuitry45 that receives the AC power from theconductors30, and payloaddata distribution circuitry39 that receives the optical signals from theoptical fibers32.
• Power conversion anddistribution circuitry45 converts the high-voltage AC to DC by rectification and filtering so as to yield 28 volt DC power required for operation of the aerial platform. That DC power is transmitted to anautopilot module53, and to the various ISR sensor ortransmitter payloads55 to power their operation. Theautopilot53 is preferably a modular auto pilot sold by Guided Systems Technology as a part of a flight control system for rotor aircraft sold under the name Hercules, with software stored thereon that is modified to operate with a rotor aircraft from a fixed-wing application, the usual configuration for that autopilot module. The DC power is also provided to the positive propulsion systems, e.g., DC motors drivingcounter-rotating propellers27, and also a DC electric motor driving the main rotor7, when the positive propulsion is activated.
• Battery power, to the extent available, is also distributed byunit45. Abattery backup57 is connected with theautopilot53, so as to power the autogyro flight controls in the event of a loss of tether power, allowing the autogyro to descend in as controlled a fashion as possible. Limited battery power may also be provided to thepayloads55,
• Thepayloads55 are the portion of the aerial platform that interacts electromagnetically with the environment to provide the enhanced range afforded by the system of the invention. The payloads are any of a myriad of possible configurations. The pay loads are circuits providing the elevated transmission and/or reception of electromagnetic signals, or other more mechanical operations such as release of chaff, etc., and may include the relevant portions of systems including the systems and capabilities set out in Table 1 below.
• The payloads used may also accommodate Ship Launched Persistent Integrated Countermeasures for Electronic Warfare (SPICE) applications, an elevated sensor program (ESP), or a LANShark Wi-Fi detection system. The payloads may also involve Anti-Submarine Warfare, Unmanned Underwater Vehicle operations, or virtually any type of electronic reliant intelligence gathering methods. The payloads are also preferably modular, so that they may be removed or swapped in and out readily depending on the particular situation requirements.

• TABLE 1
  Product	Capability provided

  Sensors

  EO/IR Ball	Locate and observe objects
  SAR	Locate, observe, and track objects
  HF-UHF DF Sensor	Locate and identify UHF transmissions
  SATCOM SIGINT	Locate and identity SATCOM transmissions
  802.11 SIGINT	Locate and identify wireless computer
  	transmissions

  Countermeasures

  Radar warning system	Early warning of radar guided missiles
  Passive missile warning	Early warning of missile launch
  Active missile warner	Early warning of missile launch
  IR CM	Infrared countermeasures
  Radar jammer	Jamming of hostile radars
  Radar decoys/missile	Seduction of radar guided missiles
  homing seducer
  Laser warner	Early warning of laser guided missiles
  Chaff/flare dispenser	Radar countermeasures

  Others

  Comms relay	Allows line of sight extension of commu-
  	nications
  Target designator	Allows designation of targets at farther
  	ranges

• Payloaddata distribution circuit49 converts the optical signals from optical fibers and back again. Referring toFIG. 8, in an exemplary combination of payload features, theground vehicle1 may generate electrical signals from aradio81, aflight control station82, and apayload HMI83 allowing for control instruction inputs. These are all transmitted as electrical signals toconverter39, sent uptether3, and the re-converted to their original form byconverter49, and are directed to the switch/amplifier and antenna of theradio payload84, anEOIR camera85 or aSIGINT payload86, and the flight control signals are directed to theflight control circuit87 of the aircraft, which sends appropriate signals to thelocal servos88 that control the autogyro control surfaces, rudders, stabilizers, rotor blade angles, etc., as is known in the art.
• Signals also proceed in the reverse direction. Video signals from theEOIR camera85, incoming radio communications fromradio antenna84, and input from theSIGINT module86 are converted to optical signals byconverter49 and sent through thetether3 down to the base vehicle, where they are converted back to electrical signals byconverter39 and transmitted to the relevant modules, e.g., theradio81, or the payload HMI, which stores the incoming data. The HMI host computer performs fusion of sensor data for real-time mission analysis.
• Processing of the incoming data signals is seen inFIG. 5. The electrical signal data fromconverter39 is formatted and distributed bycomputerized module91 running on aruggedized computer93 on the base vehicle. The data is preferably stored in a supporteddata storage device94. Optionally, the data may be sent to the vesselCommand Information Center95 for review by personnel or another ship sensor management system. The data from certain types of payloads also may be filtered and subjected to certain identification functions.
• The ruggedized computer also supports flight control program modules such as Hercules that include a realtime flight controller97, which allows a human user to manually control operation of theautogyro5 when desired, andmission planning module99, which allows the user to direct the autogyro to comply with a specified mission plan in autonomous operation, e.g., to remain at or move to certain altitudes.
• The conversion of electrical signals to optical signals transmitted in the optical fibers oftether3, and then the conversion of those signals back to electrical signals is illustrated schematically inFIG. 9.Converters39 and49 are similar to each other, and together form a novel data aggregation system (DAS) that is capable of multiplexing/demultiplexing analog radio frequency (RF), analog and digital video, Ethernet, and discrete voltage signals (e.g., TTL) over a full-duplex fiber optic link. Theconverters39 and49 are commercially available multiplexing/demultiplexing components applied to convert electrical signals to relatively higher frequency optical signals transmitted in the tether, making their detection or interception very improbable and then de-convert the optical signals locally at either end of the tether for use as common-format electrical signals.
• In the embodiment shown inFIGS. 6 and 7, thetether3 has four independentoptical fibers32. Theconverters39 and49 may constitute a plurality of parallel individual converters each operatively associated with a respective one of thefibers32 and converting electrical signals carried by electrical conductors, e.g., wires, on the respective base vehicle or aerial platform electronics to optical signals, i.e., light, transmitted over the associatedoptical fiber32. The electrical signals may be any frequency of RF or data transmission protocols, or any type of electrical signal that can be carried on a wire.
• Theconverters39 and49 also receive the light of optical signals transmitted in the fiber and converts it to electrical signals, which it transmits to electrical conductors or wires of the associated base vehicle or aerial platform electrical system connected with the converter.
• Conversion from electrical signals to light is accomplished by any method well known in the art, e.g., by LEDs, and conversion from light to electrical signals may be accomplished by, e.g., applicable types of photoelectric effect. Data may be communicated in both directions along eachfiber32.
• In one application, eachfiber32 carries a respective one of the data streams to or from theaerial platform5, providing four data signals to the payload electronics and flight control oravionics electronics51. An exemplary design for this application is illustrated in the diagram ofFIG. 10, which shows two of the four optical fibers. It will be understood that the other two fibers are configured similarly to the two in the diagram, and also that the opposite ends of the optical fibers have similar arrangements for full duplex operation of the fiber in both directions.
• Incomingelectrical signals1 and2 are sent to the converter over metal, e.g., copper, wires that may be plugged into the converter by standard types of connectors for the given type of signal. The converter includes for each incoming electrical signal a respectiveincoming signal conditioner100. Thesignal conditioner100 is configured for the specific type of electrical signal received. Theconditioner100 may comprise a simple voltage amplifier for RF signals that raises their voltage to a level for conversion to optical, or a voltage adjustment or transformer that drops the voltage if the incoming signal is a simple digital data stream. Where the signal is a parallel electrical data signal, as in, e.g., Ethernet signals, theconditioner100 converts the parallel signals into some sort of serial data stream at a voltage configured to be converted to optical signals. The conditioned electrical signals are then transmitted via a wire in the converter to alaser diode102 that receives the conditioned signals and generates corresponding light that propagates into and through the associatedoptical fiber32 to its opposite end.
• The opposing end of the fiber is essentially the same as the transmitting end, and it includes aphoto diode104 that receives light from the associatedoptical fiber32 and produces from it outgoing electrical signals, which are transmitted by wire to anoutgoing signal conditioner106. Theoutgoing signal conditioner106 performs essentially the reverse of theincoming signal conditioner100, e.g., it drops the voltage of an RF signal, increases the voltage of a digital data stream, and reconfigures a serialized Ethernet signal back into a parallel Ethernet signal at the proper voltage. The result is outgoing electrical signals that are transmitted back on electrical connections or wires that are the same as the corresponding-format incoming signals, or via different electrical connections.
• If more signals are required by the functionality of theaerial platform5 than the number of optical fibers in the tether, the signals may be multiplexed so as to be transmitted as optical signals together on the sameoptical fiber32. The multiplexing may be by any appropriate multiplex protocol, such as time or frequency multiplexing, as is well known in the communications arts.
• One design for accomplishing this is illustrated inFIG. 20. As with the embodiment ofFIG. 10, a plurality of incomingelectrical signals1,2 and3 are supplied to the converter, and each is carried by wire to anincoming signal conditioner100 that is configured for that type of signal to render it suitable for conversion to optical, as described above in regard toFIG. 10. The conditioned signal is carried by wire to a respective one oflaser diodes1,2 or3, identified asreference number102, whichdiodes102 convert the conditioned electrical signal received electrical signal to an optical light signal, as described above.
• The optical signal so generated is transmitted to an optical combiner/splitter108, which is a structure usually made of optical glass and well known in the art for combining optical data signals.Combiner108 receives the optical signals form incomingelectrical signals1,2 and3, and transmits them together overoptical fiber32. To do this, thelaser diodes102 are each selected so that the each produce light only of a respective preselected range of wavelengths that will not create interference with the optical signals generated for the other signals being transmitted on the sameoptical fiber32.
• The opposite end offiber32 has a similar arrangement and a combiner/splitter108. The light in thefiber32 is received incomponent108 and it propagates into threebranches108a,108band108c, with the light of all of the optical signals being split into three parts each containing all of the optical signals. At the end of eachbranch108a, borc,the light reaches arespective photo diode110. Thephoto diodes110 are configured to convert only the optical signals corresponding to the given signal type that it corresponds to. This may be accomplished by providing a filter in the photo diode filters out all light except the specific range of wavelengths of the associated signal, or by preselecting aphoto diode110 that is only responsive to that specific range of wavelengths.
• Thephotodiodes110 convert the respective range of wavelengths of the optical fiber light into a respective outgoing signal that is transmitted by wire to the correspondingoutgoing signal conditioner106, which operates as described above to condition the raw electrical signal from thephoto diode110 into an outgoing electrical signal of the proper voltage, data format, etc., for that type of signal. These outgoing signals are transmitted by the same or different electrical connections as provide the incoming signals of the same type.
• In the preferred embodiment, the converters at both ends of the tether are the same. A variety of arrangements can be envisioned besides the ones here illustrated. Also, other methods of multiplexing known in the art may be employed as well to combine two or more converted electrical signals along one optical fiber in the tether.
• Launch and Retrieval System
• Referring toFIG. 11, a launch and retrieval system consists of a host vehicle, particularly a vessel, having mounted thereon capture/positioning arm101 supporting horizontally supportedplatform105,winch103, tow cable (tether)3 connecting to theautogyro5. Thewinch103 includes a spooling mechanism as described previously, and the power conversion/distribution unit and launch and retrieval controller (not seen inFIG. 11) as described previously are located at the winch area. The launch and retrieval system provides active compensation for host vehicle motion for coordinated launch and retrieval.
• The capture andpositioning arm101 is a host vehicle mounted foldable aim that extends to provide a launch or capture position for the airborne vehicle. Thearm101 can be elevated or lowered, and it is selectably pivoted by operator-controlled hydraulics about a roughly longitudinalmid-center pivot connection98 or two longitudinal portions; in either position, the platform107 remains horizontal relative to the body of the host vehicle. Thearm101 directs the towing cable in a safe and controlled fashion, and can rotate 360° to allow optimal vehicle/vessel orientation. The extent of arm slew is monitored and limited to be tailored for the host vehicle layout. Automatic control coupling of the six (6) degrees of freedom of theair vehicle5 to the capture mechanism allows for dynamic capture of the vehicle.
• Thetether3 is controlled by a series ofpulleys114, and by a pair ofpulleys122 spaced up thearm101. Thetether3 is reeled out from a point near the forward end of theplatform105, and pulleys122 control thetether3 at this area, with theupper pulley122 preventing upward movement of theautogyro5, especially in close proximity to theplatform105, essentially allowing theautogyro5 to launch vertically up and rearward only, under full control, and to land on theplatform105 with purely forward and downward movement ending at themovable platform105. The capture and release phases of the airborne vehicle are assisted by the capture platform as portrayed inFIG. 12. The Launch and Retrieval System is coupled to the airborne vehicle flight control system. This control system adaption dynamically adapts to host vehicle and airborne vehicle independent motion for controlled launch and retrieval. It also adapts to compensate for varying wind and direction. The winch has a powered drum for the fiber-optic/power tow cable, level-wind and rotary joints. The Launch and Retrieval System provides the necessary commands to the winch and the vehicle during the launch and recovery phase.
• If a positive propulsion system is present, during the launch phase, the main rotor is spun up by a small motor to begin the autogyro autorotation, and the auxiliary propellers are also powered up to provide the counter-rotational forces needed against the main powered rotor (this is not necessary when the rotor is not powered). A flight control system, such as a system running Hercules software, senses whether there is sufficient lift and airspeed across the main rotor (via accelerometers and anemometer attached to the aircraft), and, responsive to a determination that the necessary wind speed is present, the flight control system, releases locking latches on the platform that hold the aircraft secured to the platform. Once airborne, and sufficiently far enough from the launching vessel, the Hercules assesses flight dynamics (wind speed airspeed, wind direction, altitude, and if the relative wind speed is viable for powerless flight, it will disengage the three motors. During the retrieval phase, the Hercules reengages the propellers and main rotor motor to provide the needed lift and maximize maneuverability. While the aircraft is being drawn into the capture platform (winched in) the Hercules maintains a positive pitch to keep the propellers clear of the capture platform. As the landing skids contact the platform deck, the latching mechanism thereon automatically locks the aircraft onto the platform, at which point the Piccolo will disengage all motors.
• The flight system with Hercules software has a Built In Test (BIT) function that constantly performs diagnostics to assure functionality and mission readiness. Communications, servo actuators, data links, motor control, tether integrity are continuously checked and any functional discrepancy is reported.
• The system flight controller easily controls the aircraft in flight, and during launch or retrieval. The flight controller is also used to build the predetermined flight parameters that will be followed during the mission.
• Once the base vessel is outfitted, operating the system is simple and straightforward according to the following method steps:
• • 1. Select payload configuration (payload pylori) and program mission parameters
  • 2. Install payload pylori onto aircraft platform
  • 3. Turn on the Piccolo auto pilot
  • 4. Confirm from that the startup BIT has successfully run
  • 5. Confirm that the pre-flight mission data is loaded
  • 6. Enable preflight/launch sequence (sailing direction, wind speed deploy aircraft platform)
  • 7. Authorize launch sequence
  • 8. Deploy aircraft to desired altitude, distance and offset.
  • 9. Monitor for automated system alerts while employing embarked sensor.
• The system of the invention is designed for minimal or no maintenance and ease of use. There are no routine maintenance operations, beyond battery recharging or replacement, and therefore, no requirements for special or general purpose test equipment. An extremely low cost and high MTBF minimizes the need for spares or a repair facility. A modular design and construction of the aircraft facilitates any necessary repairs. The BIT routine provides a high degree of confidence that the auto-pilot and flight control functions are fully working.
• FIG. 12 represents the system Launch and Recovery Arm in the both launch and recovery operations. Generally described, thearm101 andplatform105 are elevated in the launch phase, and the tether is reeled out while the autogyro is piloted by the launching computer system, and guided to its operational altitude. In recovery, theplatform105 is generally lowered to its lowest position, and the autogyro is reeled in and piloted to a soft landing thereon.
• FIG. 13 shows an alternate embodiment of autogyro. This embodiment has tworotor blades111 supported on amast structure113 of carbon fiber. Themast structure113 is supported on side rails similar to the side rails115 of the previous embodiment, except that they are tubular and of carbon fiber as well. A modifiedtail structure116 has controllable stabilizers and rudders for control of the autogyro movement. Front and rearcylindrical tubes117 and119 are similar to those of the previous embodiment and are supported betweenside tubes115. Landing skids121 of carbon fiber are also connected toside tubes115. The use of carbon fiber for most of the components further reduces the likelihood of detection, and also reduces the weight of the aircraft.
• FIG. 14 shows an elevational view of one of theautogyro cylinders15 or119. Thecylinder body141 is a tube of carbon fiber material with a row of holes therein for connection to the rest of the autogyro, or for securing internal parts to thetube141. The longitudinal ends of thetube141 are each covered with a respectivehemispherical cover143. The connection between thecovers143 and thetube141 is watertight.
• A number of payload antennas andother structures143 to131 operatively associated with payload circuitry inside thecylinder pod15 extend through thetube141. The apertures in thetube141 through which these structures extends are also sealed by surrounding sealing structures, e.g.,composite bulkheads153 and155, so as to be watertight.
• A great deal of heat is generated by the operation of the payload circuitry inside thecylinder15. This heat is at least partially dissipated by allowing flow of air through thecylinder15 between front andrear ventilation openings157 and159 in the hemispherical covers143. Theseopenings157 and159 are the only possible entry or egress for air or water into thecylinder15.
• Referring toFIG. 15, cooling flow of air through thetube141 is aided by arotary fan161 that is powered by the aircraft power control DC current. Thefan161 forces air to flow through thetube141 over the payload circuitry generally indicated at163. Thecircuitry163 is preferably connected with heat sinks having heat dissipation vanes that transfer heat as effectively as possible to this airflow.
• Thepayload circuitry163 is potentially made up of very costly components that could be destroyed or damaged if water were to enter thecylinder15, as, for example, if the autogyro were to crash into the sea. To guard against this, in each of the end covers143, asolenoid165 is supported. When activated, the solenoid clamps a door shut over the associatedopening157 or159, sealing it with a watertight closure, and completely sealing thecylinder15 against any entry of water that might damage thepayload circuits163.
• The solenoids are connected with the flight controls so that, responsive to a determination of a catastrophic event, such as a total power failure or some other indication of an imminent crash of the aircraft that might involve hitting the water, the solenoids close the watertight doors and seal the cylinder.
• In addition, a water sensor may be mounted adjacent eachopening157 or159. In the event that there is contact with water, the water sensor will produce a signal indicative of the presence of water. Responsive to that signal, both of thesolenoids165 will release so as to seal watertight doors overopenings157 and159, protecting the interior of thecylinder15 from water incursion.
• FIG. 16 shows the structure of the solenoid and the sealing apparatus in detail, with the watertight seal closed, i.e., preventing water from entering thecylinder15.
• The sealingdoor member170 is of elastic flexible material, and it has a mountingportion172 affixed to the vertical wall, a bend at its upper end, and then the sealingdoor portion174. The material of themember170 is elastomerically biased such that the sealingdoor portion174 moves to the position shown, sealing the opening to the fan by covering the opening defined by the interior passage of tubularinsert liner piece175 and pressing against sealinggasket177 to seal the opening.Liner piece175 is fixedly supported in the passage, and it provides a shoulder surrounding the passage through it, to which shoulder thegasket177 is affixed, whether thedoor174 is closed or open.
• At the start of operation, thesolenoid165 is actuated, which pulls on nylon coatedrope171 which extends through Teflon bearing173 and is fixedly attached to thedoor sealing portion174 ofelastic part170. This results in a pull on the sealing door portion downward away from its engagement with sealinggasket177, opening the space inpiece175 and allowing air to flow through.
• In the event of a power failure, thesolenoid165 releases, and therope171 is also released. No longer being held in the open position byrope171, the elastic nature of the sealingdoor member170 biases the sealingdoor portion174 upward again, so that it covers the opening and seals in engagement withgasket177. This clamps shut the access to the interior through the moldedexhaust vent179 incylinder15, protecting its contents.
• The described structure is however purely exemplary, as other systems may readily be designed to accomplish this end of sealing the opening.
• FIGS. 17 to 19 show another embodiment of autogyro for use in a system according to the invention.
• Referring toFIG. 17, theautogyro201 has arotor203 with two rotor blades205 (seeFIG. 19) supported on amast structure207 of carbon fiber. Therotor203 is supported so as to be pivotable relative to themast structure207 aboutpivot209. The angle of therotor203 relative to themast207 is adjustable by the avionic electronics and controls of theautogyro201, and therotor203 is moved to the determined angle byhydraulic cylinders211, or similar devices, controlled by the autogyro electronics.
• Mast structure207 is secured at its lower end to left and right side frames213, which at their lower ends are attached fixedly to, respectively, left and right side rails215 similar to the side rails of the previous embodiment, that are tubular and of carbon fiber as well. Aweb217, best seen inFIG. 18, is also connected with the lower ends of the side frames213. The side frames213 are substantially planar, and have cut-outs to reduce weight.
• Theweb217, side frames213 and bottom of themast structure207 together define a space supporting thereincylindrical payload modules219 and221. Thepayload modules219 and221 are essentially the same as thepayload modules117 and119 of the previous embodiment, and are affixed on their lateral sides to the side frames213.
• Module221 is supported directly above and slightly rearward of themodule219. This renders thevehicle201 more compact and structurally rigid, and the physical enclosure as well as the relative positions of themodules219 and221 provides more structural protection in case of an impact. Themodules219 and221 are provided, as in the previous embodiments, with openings forward and aft that permit passage of air through the module so as to cool the electronics in it. In addition, the modules are provided with safety mechanisms that, responsive to detection of contact with water or other indication of a non-normal landing of the vehicle, e.g., a crash, close watertight doors that seal those openings so that each module becomes watertight.
• The side rails215 support atail structure223 at their rearward ends. Thetail structure223 includes ahorizontal stabilizer225 and avertical tail section227. Thetail section227 is formed of a pair of laterally spacedvertical plates228pivotably supporting rudders229.Rudders229 are tied to each other so as to move together, and are moved to the proper position for the flight conditions by acylinder231 controlled by the autogyro flight control electronics, either operating automatically or by an operator manual control at the base vehicle for control of the autogyro movement.
• Landing skids235 of carbon fiber are also connected to side frames213. Theskids235 are formed of carbon fiber tubes237 extending obliquely from brackets239 toangle pieces241 that connect with and support horizontal carbon-fiber cross tube243. Themast207, the side frames213, the side rails215, and the stabilizer and rudder are made of carbon fiber. The use of carbon fiber for most of the components of this embodiment reduces the likelihood of detection by electromagnetic sensors or radar, and also reduces the weight of the aircraft.
• The mechanical connection part of the end of the tether is secured to abridle structure241 extending between the front ends of side rails215. The upper end of thetether3 is secured in aKellems grip connector243 secured by releasable link orkarabiner245 to aU-shaped bridle member147, secured in turn byloops249 to the front ends of the side rails215. The electrical and optical parts of thecable251 extend past this point and hook up to respective watertight connections on the underside ofmodule219.
• Module219 preferably contains the power and signal converters linked to the power and optical fibers of the tether. It also contains the payload electronics for the aerial platform.
• Module221 preferably contains the on-board avionics electronics for control of the flight operations of the autogyro. A further watertight cable extends frommodule219 tomodule221, and carries the DC current to it to power the avionics. The cable between the modules also transmits flight-command data signals sent up the tether from the base vehicle frommodule219 to the avionics circuitry in thesecond module221.
• The terms used in this disclosure should be read as terms of description rather than of limitation, as those of skill in the art with this disclosure before them will be able to make modifications and amendments thereto without departing from the spirit of the invention.

Claims (38)

What is claimed is:

1. A method for interaction with an environment around a vehicle, said method comprising:

providing an airborne platform connected by a tether to the vehicle, said airborne platform remaining aloft at least in part by airflow relative to the airborne platform;

transmitting electrical power from the vehicle to the airborne platform via a power conductor in the tether; and

receiving the electrical power in airborne electronic payload circuitry on the airborne platform, the airborne electronic payload circuitry using said electrical power to engage in the interaction with the environment; and

carrying upward optical data signals between the vehicle and the airborne platform via an optical fiber in the tether;

converting the upward optical data signals received at the aerial platform to received electrical signals and providing the received electrical signals to the payload circuitry; and

generating local electrical signals in the payload circuitry responsive to the interaction with the environment,

converting the local electrical signals on the aerial platform to downward optical signals, and

transmitting the downward optical data signals to the vehicle via the optical fiber, or via another optical fiber in the tether.

2. A method as described inclaim 1, wherein the airborne platform is an autogyro having a rotor with blades that co-act with air so as to maintain lift for the autogyro.

3. A method as described inclaim 2, wherein the electrical power comprises AC current, and the transmitting of the electrical power includes using a transformer on the AC current such that the AC current has a voltage in a range of 480 and 2000 volts and a power of 700 to 2000 watts.

4. A method as described inclaim 3, wherein the electrical power is at least partly converted in the airborne platform to DC current.

5. A method as described inclaim 2, wherein the electronic payload circuity is contained in one or more modules supported on the autogyro, said modules having forward and rearward openings therein configured so that air flows therebetween inside the module so that the payload electronics are cooled thereby.

6. A method as described inclaim 2, wherein the module or modules are configured to close said openings so as to make the module or modules watertight in the event of a crash of the autogyro.

7. A method as described inclaim 1, and further comprising converting electrical signals carried in electrical conductor circuitry in the vehicle to the optical signals.

8. A method as described inclaim 1, wherein said generating of the local electrical signals comprises receiving electromagnetic signals and converting the electromagnetic signals to the local electrical signals.

9. A method as described inclaim 1, and further comprising operating control avionics of the airborne platform based on the received electrical signals.

10. A method as described inclaim 1, and further including sensing an aspect of the environment of the airborne platform with a sensor connected with the payload circuitry so as to generate sensor signals, and the generating of the local electrical signals comprising converting the sensor signals into the local electronic signals.

11. A method as described inclaim 1, wherein the payload circuitry includes electronic or mechanical electronic warfare countermeasures that are initiated responsive to the received electrical signals.

12. A method as described inclaim 1, wherein the tether comprises a plurality of metallic electrical conducting wires, a plurality of optical fibers and a load-bearing sheath extending between the vehicle and the airborne platform.

13. A method as described inclaim 1, wherein the vehicle is a sea-going maritime vessel.

14. A method as described inclaim 1, wherein the payload electronics are configured to provide electronic warfare or defense capabilities to the vehicle.

15. A system providing a vehicle with electronic operations at a distance from the vehicle, said system comprising:

a tether connected with the vehicle and extending upwardly therefrom;

an airborne platform connected with the tether and secured thereby so as to remain aloft in an area of the vehicle at least partly by airflow relative to the aerial platform;

the airborne platform having airborne electronic payload circuitry supporting the electronic operations; and

said tether including an electrical conductor supplying electrical power from the vehicle to the aerial platform; and

said tether including at least one optical fiber linked with the airborne electronic payload circuitry and with electronic base circuitry on said vehicle;

the optical fiber in the tether carrying optical data signals to the airborne platform from the vehicle or to the vehicle from the airborne platform such that the electronic base circuitry on said vehicle co-acts with the airborne electronic payload circuitry during the electronic operations.

16. A system according toclaim 15, wherein the vehicle is a maritime vessel.

17. A system according toclaim 16, wherein the tether comprises a tensile load bearing portion extending from the vessel to the airborne platform being of adequate strength to retain the airborne platform connected with the maritime vessel, a plurality of metallic electrical conductors, and a plurality of optical fibers, and

the system further comprises

a winch selectively reeling in or reeling out the tether, and

a stationary or movable platform on the vessel, said movable platform supporting the airborne platform thereon before launch and after recovery, said movable platform being selectively moved to a first elevated height and to a second height lower than the first elevated height;

wherein, during launch, the airborne platform is supported on the platform and the winch reels the tether out; and

wherein, during recovery of the vehicle, the winch reels the tether in.

18. A system according toclaim 16, wherein the airborne platform is an autogyro connected to an end of the tether, the autogyro having a rotor and a frame supporting one or more generally cylindrical modules of carbon fiber material, wherein the electronic payload circuity is contained in said modules, said modules having forward and rearward openings therein configured so that air flows therebetween inside the module so that the payload electronics are cooled thereby, and the module or modules are configured to close said openings so as to make the module or modules watertight in the event of a crash of the autogyro.

19. A system according toclaim 18, wherein the autogyro has structural members and control surfaces formed of carbon fiber material.

20. A system according toclaim 16, wherein the electronic payload comprises one or more component systems selected from the group consisting of sensors detecting visible objects, electromagnetic detection system sensors, radar systems, passive or active missile detection systems, laser detection systems, communication jamming or radar jamming systems, electronic warfare countermeasures, communications relay, and target designation systems.

21. A system according toclaim 20, wherein the electrical power is AC current having a voltage in a range of from 480 volts to 2000 volts, and the airborne platform supports therein a power distributer that converts the AC current to DC current at a lower voltage, and supplies that DC current to the electronic payload.

22. A system according toclaim 21, wherein the optical fibers each have two opposing ends, one of the ends being proximal to the host vehicle and the other of the ends being proximal to the aerial platform, one of the ends having a first converter converting electrical signals carried in a first wire connected therewith to optical light signals transmitted in the optical fiber, and the other of the ends having a second converter converting the optical light signals in the optical fiber to electrical signals and supplying the electrical signals to a second wire connected therewith.

23. A system according toclaim 22, wherein the first converter also converts optical signals in the optical fiber to other electrical signals, and the second converter also receives further electrical signals and converts them to other optical light signals in the optical fiber such that data may be transmitted in both directions in the optical fiber.

24. A system according toclaim 17, wherein the tether further has a conductor configured to carry electricity from lightning in the event of a lightning strike on the airborne platform.

25. An airborne platform providing electronic surveillance, communication or electronic warfare or defense capabilities, said airborne platform comprising:

an autogyro configured to be secured to an end of a tether having conductors carrying AC current and optical fibers carrying optical signals;

the autogyro including a frame supporting a rotor with rotor blades providing lift from passing air, and a stabilizer structure with control surfaces;

the frame supporting a generally cylindrical module supporting therein payload electronics configured to support said electronic surveillance, communication or electronic warfare or defense capabilities and avionic electronics controlling flight operation of the autogyro;

the module receiving the AC current and the optical signals from the tether, said module having a power converter converting the AC current to DC current and supplying the DC current to the payload and avionic electronics, and a signal converter converting the optical signals into electrical signals and transmitting said signals to the payload and avionic electronics.

26. An airborne platform according toclaim 25, wherein the electronics are supported in two generally cylindrical modules and the frame includes laterally spaced side panels supporting the modules therebetween;

one of the modules being supported above the other of said modules.

27. An airborne platform according toclaim 25, wherein the module has openings therein permitting passage of air through the module such that the electronics therein are cooled.

28. An airborne platform according toclaim 27, wherein the module has closures that close the openings and render the module watertight responsive to a detection of contact with water or a non-normal landing.

29. An airborne platform according toclaim 26, wherein the autogyro further comprises a mast supporting the rotor, and said mast, said control surfaces, said modules and the side panels of the frame are of carbon fiber material.

30. A system linking a ground vehicle with an airborne platform, said system comprising:

a tether having

a mechanical portion providing sufficient tensional strength for retaining the airborne platform connected by the tether to the ground vehicle;

a metallic electrical conductor extending from a first end of the tether to an opposing second end of the tether, said conductor being configured to transmit AC current having a voltage of at least 400 volts and a power level of at least 600 watts;

at least one optical fiber extending from the first end to the second end of the tether;

first and second converters at the first and second ends of the tether, respectively;

each of said converters comprising

an electrical connection receiving incoming electrical signals,

an electrical-to-optical conversion unit connected with the electrical connection and converting said incoming electrical signals to outgoing optical signals and transmitting the outgoing optical signals over the optical fiber, and

an optical-to-electrical conversion unit receiving incoming optical signals transmitted through the optical fiber and converting said incoming optical signals to outgoing electrical signals and transmitting the outgoing electrical signals to the electrical connection.

31. The system ofclaim 30, wherein the system further comprises a power supply at one end of the tether with a step-up transformer supplying the AC current at a voltage in a range of 480 and 2000 volts and at a power level of 700 to 2000 watts, and a power processor at the other end of the tether receiving the AC current from the metal conductor and converting the AC current to DC current.

32. The system ofclaim 30, wherein the tether has at least one additional conductor carrying a different phase of the AC current.

33. The system ofclaim 30, wherein the tether has at least one further optical fiber, and wherein the incoming electrical signals comprise a plurality of electrical data signals, the electrical-to-optical conversion unit converting said electrical data signals into outgoing optical data signals each transmitted on a respective one of the optical fibers.

34. The system ofclaim 30, wherein the tether has at least one further optical fiber, and wherein the incoming electrical signals comprise a plurality of electrical data signals, the converter unit converting said electrical data signals into outgoing optical data signals, two of said optical data signals being transmitted together on one of the optical fibers.

35. The system ofclaim 34, wherein said optical data signals are time or frequency multiplexed.

36. The system ofclaim 34, wherein the conversion units are configured to provide multiplexing and demultiplexing of electrical signals including at least one of the group consisting of radio frequency (RF) signals, analog and digital video signals, Ethernet data signals, and discrete voltage signals, including Transistor-Transistor Logic (TTL).

37. The system ofclaim 30, wherein the system further comprises a grounded connection and the tether has a lightning rod conductor extending therealong configured to carry electrical energy of a lightning strike along the tether to said grounded connection.

38. The method according toclaim 13, and further comprising selectively reeling in or reeling out the tether using a winch on the vehicle, and

wherein a movable platform is carried on the vessel, said movable platform supporting the airborne platform thereon before launch and after recovery, said movable platform being selectively moved to a first elevated height and;

during launch, supporting the airborne platform on a movable platform on the vessel, elevating the movable platform to a first elevated height, and reeling the tether out with the winch; and

during recovery of the airborne platform, lowering the movable platform to a second height lower than the first elevated height, and reeling the tether in with the winch.

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